1. Technical Field
Embodiments of this disclosure generally relate to a fixing device and to an electrophotographic image forming apparatus incorporating the fixing device.
2. Related Art
Some typical heating devices include a heat-resistant film, a heat generator and a pressure member. The heat generator is fixedly supported at the center in a lateral direction on one side of a heater substrate and divided into six sub-heat generators in a direction perpendicular to a direction in which a recording medium is conveyed. The pressure member is disposed facing the heat generator via the heat-resistant film. The pressure member and the heat generator are pressed against each other via the heat-resistant film to form an area of contact referred to herein as a fixing nip therebetween. The recording medium is conveyed to the fixing nip, between the heat-resistant film and the pressure member, thereby passing through the fixing nip together with the heat-resistant film. Thus, heat energy is transmitted from the heat generator to the recording medium via the heat-resistant film.
Such heating devices are capable of significantly reducing energy consumption by selectively supplying power to the sub-heat generators for individually heating their respective images, thereby reaching a fixing temperature.
In addition, the heating devices include electrical conduction paths to supply power to the heat generator. The electrical conduction paths are provided, e.g., in a substantially symmetrical manner, on both sides of the heater substrate in the lateral direction thereof with the six sub-heat generators interposed therebetween.
Some other typical heating devices, specifically image heating devices, include a heating rotator to heat an image carried by a recording medium, and a heating member to contact and heat the surface of the heating rotator. The heating member includes a heater having a heat generator on a heat-conductive substrate, and a heat-conductive member that contacts the substrate. The heat-conductive member is made of a material having a higher heat conductivity than a material of the substrate. Thus, the typical image heating devices have a heating area allowing both of the heater and the heat-conductive member to heat the surface of the heating rotator.
With such a configuration, the typical image heating devices can shorten warm-up time and lower the temperature of the heater.
Some of them also include substantially one heat generator disposed at a position downstream in a rotational direction of a fixing roller in the heating area.
However, with such a typical wiring pattern, in which electrical conduction paths are disposed on both sides of the heater substrate in the lateral direction thereof, with the heat generator interposed therebetween in a substantially symmetrical manner, a space, that is, a line width of wiring is insufficient to dispose the heat generator having a plurality of heat-generating areas, at a position closer to the fixing nip.